Action with an actually touchable real object, such as writing characters on a paper with a pen, cutting a cooking ingredient in a kitchen, and playing a card game, is unable to be performed in the same space as action using digital information with a personal computer or a smartphone, for example. However, it is anticipated that, in future, digital information is superimposed on a real world using a projector for example, to enable a work in a space which integrates a real world and a digital information world. Some examples are writing a formula on a paper to automatically generate a graph and projecting a cut line on a cooking ingredient to cut it appropriately according to a recipe. AR application for realizing such processes is, for example, the technology disclosed in Patent Literature 1 and others.
A preceding technology that presents digital information on a real world is, for example, a technology using a projector, a head mount display (HMD) of a see-through type, a camera-equipped display such as a smartphone, or the like. In the following, such work space that integrates a real world and digital information is referred to as “extended work space”.